How to use 'BAPI ENTRYSHEET CREATE'.

I am asked to use the BAPI 'BAPI_ENTRYSHEET_CREATE' to create a service entry sheet=2E I have the Purchase order number(EBELN) and the line item(EBELP)=2E From this BAPI 'BAPI_ENTRYSHEET_CREATE' it seems i need to get the entry sheet number and pass it to BAPI 'BAPI_ENTRYSHEET_RELEASE' to release the service entry sheet=2E

My problems are=2E

1=2E I am new to BAPI, i came to know they are just like Function Modules to which you need to pass values and get the results=2E(Eventhough concept wise they are methods to BOR-business object Repository)=2E

2=2E I do not know what values are to be passed to BAPI 'BAPI_ENTRYSHEET_CREATE' to get the entry sheet number=2E

If any one has worked on this or has idea of how to use it, Please share it with me=2E Thanks in advance for your ESTEEMED responses=2E